[Reaction of osseous tissue and the osteoclast population in rats to biphosphonates and vitamin D3 under conditions of hypokinesia].

Oral administration of hydroxy-dimethyl aminopropylene biphosphonate (DMAP) at a dose of 0.5 mg/kg increased the volume density (mass) of trabecular bone in the tibial metaphysis of untreated rats and helped to maintain it at the normal level in hypokinetic rats. Oral administration of hydroxy-ethylidene biphosphonate (OEDP) at a dose of 20 mg/kg and vitamin 24,25(OH)2D3 at a dose of 1,25 micrograms did not induce any quantitative changes in bones of untreated or immobilized rats. The combined treatment with either biphosphonate and vitamin D3 exerted a similar effect as compared to that of biphosphonates used singly. During hypokinesia the total amount of osteoclasts declined. This effect was also seen in response to biphosphonates and vitamin D3. The two biphosphonates produced an opposite effect on the osteoclast population in untreated animals: it increased in response to OEDP and decreased in response to DMAP. In contrast to OEDP, low doses of DMAP can efficiently inhibit bone resorption upon various routes of its administration and can be viewed as a preventive and therapeutic drug in the case of osteoporosis.